This invention relates in general to a hand-held, single patient use, positive expiratory pressure respiratory therapy device and, in particular, to a positive expiratory pressure respiratory therapy device utilizing a nonlinear orifice for adjusting and maintaining a desired pressure oscillation frequency in accordance with a predetermined pressure range of a patient""s expiratory air.
Persons who suffer from pulmonary problems that result in large amounts of mucus being produced in the lungs often require assistance in the removal of these secretions. If these secretions are allowed to remain in the lungs, airway obstruction occurs resulting in poor oxygenation and possible pneumonia and/or death. One of the clinically recognized treatments for this condition is a technique known as positive expiratory pressure therapy or PEP. With PEP therapy, a patient exhales against a resistance to generate expiratory pressure at a substantially constant rate of flow. Prescribed expiratory pressures are generally in the range of 10-20 cm H2O, although other pressure ranges and pressures can be used.
PEP therapy has been documented by clinical research as equal to or superior to standard chest physiotherapy techniques which, while effective, are time consuming and not well tolerated by many patients who have difficulty breathing for extended periods of time in certain positions required for administration of standard chest physiotherapy. Accordingly, PEP therapy is believed to provide significant advantages to patients suffering from cystic fibrosis, and is felt to be an eventual replacement for chest physiotherapy for many patients.
In the use of PEP therapy, a patient breathes through an orifice restricter to generate a positive pressure in the lungs during exhalation, with the pressure falling to zero at the end of exhalation. By selection of a proper-sized orifice, a given pressure is determined for the exhalation flow rate generated by an individual patient. This extended, substantially constant flow, elevated-pressure exhalation has been shown to be effective for moving secretions trapped in the lungs to the larger airways where the secretions can then be removed through coughing.
The PEP therapy devices presently in use are very effective in the administration of the aforementioned type of PEP therapy. While an expensive pressure gauge can be connected to such a device to display the expiratory pressure being exerted by the patient, proper administration of the PEP therapy does not require the determination by the patient of an exact gauge pressure. Accordingly, PEP therapy can be properly administered as long as the patient can be made aware that the expiratory pressure is being maintained within a proper predetermined pressure range. Such a satisfactory PEP therapy device is disclosed in R. A. Niles et al U.S. Pat. No. 5,598,839, POSITIVE EXPIRATORY PRESSURE DEVICE, wherein a single user respiratory therapy device includes a pressure range monitoring unit which provides a patient with a visual feed-back to monitor the correct use of a PEP device for enhancing the benefits of positive expiratory pressure therapy.
It has also been found that in the treatment of patients having chronic obstructive pulmonary disease (COPD), chronic bronchitis, cystic fibrosis, atelectasis, or other conditions producing retained secretions, treatment with PEP therapy is improved by combining positive expiratory pressure therapy with airway oscillation and intermittent airflow acceleration. Some studies of chronic bronchitis patients have shown that 86% were able to expectorate mucus easier and more efficiently compared to 48% in a control group, and in another study, mucus clearance increased from 2.8 ml to 10.1 ml through the use of such enhanced PEP therapy.
The present invention comprises an enhanced PEP therapy device which provides a variable frequency positive expiratory pressure by utilizing a nonlinear orifice for adjusting and maintaining a desired pressure oscillation frequency in accordance with a predetermined pressure range of a patient""s expiratory air.
It is, therefore, an object of this invention to improve positive expiratory pressure devices.
Another object of this invention is to utilize a variable frequency expiratory pressure in a positive expiratory pressure therapy device.
A further object of this invention is obtain a variable frequency positive pressure in a positive expiratory pressure device by utilizing a nonlinear orifice to adjust and maintain a predetermined pressure oscillation frequency.
These and other objects are attained in accordance with the present invention wherein there is provided a hand-held, single patient use, positive expiratory pressure respiratory therapy device utilizing a nonlinear orifice for adjusting and maintaining a desired pressure oscillation frequency in accordance with a predetermined pressure range of a patient""s expiratory air.